Specific extra-cellular proteinaceous materials are associated with certain fascinating carcinomas which have both a dominant pattern of inheritance as well as endocrine function. Obtaining quantities of this specific protein material should allow for future studies aiding in the determination of mechanisms involved in cellular control as well as production, storage and release of endocrine substances. Purification of the extracellular protein, "amyloid," in certain endocrine tumors will be done following partial purification by centrifugation techniques. This hyaline material is termed amyloid because of ultrastructural and histochemical properties. Purification by chromatographic techniques in guanidine with reducing agents will be followed by characterization including amino acid sequence analysis, precisely as has been done for amyloid protein from other sources. Preliminary work in this laboratory as well as the extensive histochemical analysis of A.G.E. Pearse indicates that this material will represent a product or portion of a product of these hormonally active tumors. Characterization of this material should provide a tool for gathering further insight into cellular mechanisms of activity and control in these tumors.